CORRECTED - CORRECTED-UPDATE 3-ScanSource cuts Q3 sales outlook, shares fall

(Corrects paragraph 7 to say that ScanSource's unit Catalyst Telecom is the biggest customer of Avaya Inc)

(Recasts; adds byline, CFO comments, updates share price)

By Savio D'Souza

Bangalore, April 7 (Reuters) - ScanSource Inc (SCSC.O: Quote, Profile, Research), a distributor of bar code scanners, slashed its third-quarter sales forecast, hurt by lower-than-expected sales at a distribution unit and slowing overseas growth, sending its shares down more than 19 percent.

The company now expects sales of $509 million to $515 million for the quarter ending March 31, compared with its prior view of $550 million to $570 million.

Analysts on average expect revenue of $562.6 million for the period, according to Reuters Estimates.

ScanSource said a change in the vendor program caused delays in purchases during the quarter, resulting in weak sales at its Catalyst Telecom unit, which sells voice, data and converged communications equipment.

The company warned that the changed program may have resulted in loss of market share.

The vendor was communications equipment company Avaya Inc, Chief Financial Officer Richard Cleys told Reuters by phone. Catalyst Telecom group is the largest customer of Avaya, he added.